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Casirivimab-Imdevimab and Sotrovimab During SARS-CoV-2 Delta Variant Surge
Quick Takes
- This report consists of two studies (a propensity-score matched cohort study and a randomized trial) examining the comparative effectiveness of the monoclonal antibodies casirivimab-imdevimab and sotrovimab in the treatment of mild to moderate COVID-19 caused by the SARS-CoV-2 Delta variant.
- Both casirivimab-imdevimab and sotrovimab treatment were associated with a reduction in hospitalization or death compared to no treatment. Effectiveness was similar between both therapies.
- The relevance of these findings in the era of Omicron predominance is unclear.
Study Questions:
Are the monoclonal antibodies (mAb) casirivimab-imdevimab and sotrovimab effective in the treatment of mild to moderate coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant?
Methods:
This report includes data from two studies: 1) a propensity score–matched cohort study of mAb treatment versus no mAb treatment, and 2) a randomized comparative effectiveness trial of casirivimab-imdevimab and sotrovimab. The single-center cohort consisted of patients positive for SARS-CoV-2 who received mAb treatment from July 14–September 29, 2021. For the trial, patients were randomized to either intravenous casirivimab-imdevimab or sotrovimab according to a system therapeutic interchange policy. The primary outcome was hospitalization or death within 28 days of mAb treatment.
Results:
A total of 3,069 patients (mean age 53 years, 56% women) were included in the prospective cohort study, with 1,023 receiving mAb treatment and 2,046 with no mAb treatment. mAb treatment was associated with reduced risk of hospitalization or death (relative risk [RR], 0.40; 95% confidence interval [CI], 0.28-0.57) compared with no treatment. Both casirivimab-imdevimab (RR, 0.31; 95% CI, 0.20-0.50) and sotrovimab (RR, 0.60; 95% CI, 0.37-1.00) were associated with reduced hospitalization or death compared with no mAb treatment. In the clinical trial, 2,454 patients were randomized to receive casirivimab-imdevimab and 1,104 patients were randomized to receive sotrovimab. The median (interquartile range) hospital-free days were 28 (28-28) for both mAb treatments, the 28-day mortality rate was <1% (n = 12) for casirivimab-imdevimab and <1% (n = 7) for sotrovimab, and the hospitalization rate by day 28 was 12% (n = 291) for casirivimab-imdevimab and 13% (n = 140) for sotrovimab. The difference was not statistically significant between both treatments.
Conclusions:
Both casirivimab-imdevimab and sotrovimab were effective in reducing the risk of hospitalization or death in nonhospitalized patients with mild to moderate COVID-19 caused by the Delta variant, with similar effectiveness.
Perspective:
The Delta variant of SARS-CoV-2 was the predominant SARS-CoV-2 strain in July of 2021 and was the deadliest. Monoclonal antibodies to different epitopes of the SARS-CoV-2 spike protein were developed to mitigate the progression to severe COVID-19. This study reiterates previous studies showing effectiveness in these therapies. However, with the evolution of the pandemic and the rise of new variants (Omicron and its subvariants), whether these treatments remain useful is questionable. Recently, the Food and Drug Administration withdrew its authorization for the use of sotrovimab, as it is unlikely to be effective for treatment against the BA.2 variant. Fortunately, there has been a steady improvement in COVID-19–related outcomes, with a decrease in hospitalization and deaths related to COVID-19. In addition, the availability of oral medications such as Paxlovid are also effective alternatives to antibody infusions, putting into question the need for antibody infusions.
Clinical Topics: COVID-19 Hub, Prevention, Novel Agents
Keywords: Antibodies, Monoclonal, COVID-19, Epitopes, Hospitalization, Primary Prevention, Risk, SARS-CoV-2, Spike Glycoprotein, Coronavirus, Treatment Outcome
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